Refrigerant controlling and expansion apparatus



3B, 394. J. N. ROTH 2,413,335

REFRIGERANT CONTROLLING AND EXPANSION APPARATUS Original Filed May 17, 1941 I r w; jrrverfifl Patented ec. 3l, 1946 REFRIGE ii CONTROLLING AND EXPAN- SION APPARATUS Joseph N. Roth, lding, Mich, assignor, by mesne assignments, to Montcalm, Incorporated, Greenvilie, Mich a corporation of Michigan Ori -11 application May 17, 1941, Serial No.

394,031. Divided and this application September 11, 1943,=Serial No. 501,936 7 Claims.

This invention relates to refrigerant controlling and expansion apparatus, and more particularly to a, capillary tube and an evaporator of the continuous tubing type, with an improved means for connecting them.

One feature of this invention is that it provides improved means for operatively associating an automaticaily controlled capillary tube and an evaporator, particularly where the two lle primarily on opposite sides of aninsulated wall, as the back wall of the food compartment of a refrigerator; another feature of this invention is that it increases the efficiency of the refrigerator by preventing frosting back on the inlet side of the evaporator; and yet another feature of this invention is that the capillary tube and its associated receiver may be' readily separated from the evaporator in the field for servicing or replacement. Other features and advantages of this invention will be apparent from the following specification and the drawing, in which:

be met by the use of an accumulator, but must be solved in some other way.

I have solved this problem by providing a section of straight tubing of small diameter extending through one of the insulated walls of the food compartment and having its inner end connected to the evaporator, and by having the capillary tube terminate in a straight portion received by such section of tubing in a close but removable fit, the section of tubing and the capillarytube being removably sealed together, outside of the food compartment, by flanges and bolts.

Referring now more especially to the particular embodiment of my invention illustrated in the Figure 1 is a partial vertical cross sectional view of a domestic refrigerator of the absorption type; Figure 2 is a sectional view along the line ti of Figure 1; and Figure 3 is a sectional view along the line 3-3 of Figure 2.

This application is a divisional of my copending application Serial No. 394,031, filed May 17, 1941, which issued as Patent No. 2,334,219 on November 16, 1943; and a continuation-in-part of 'my copending application Serial No. 361,629,

filed October 17, 1940, which issued as Patent No. 2,339,815 on January 25, 1944.

Flat plate or shelf types of evaporators have met with increasing favor in domestic refrigerators, yet such evaporators present certain problems, particularly with respect to uniform cooling over the entire area of theshelf of the evaporator at various refrigeration rates, claims to my improved arrangement in this regard being incorporated in the first of my above-mentioned patents. In addition, where a capillary tube is used, with an arrangement for automatically controlling the rate of flow through the capillary, the

continuous absorption type this problem cannot accompanying drawing, a domestic refrigerator is shown having a food compartment it with insulated walls, including the back wall i i. While the arrangement which is the subject matter of this application has advantages in any type of refrigerator, it was particularly designed for a continuous absorption domestic refrigerator, where its advantages are realized to the fullest. The evaporator is shown at the top of the food compartment Ill and comprises a sheet metal box I2 and upper and lower loops of tubing, here identlfled as 13a and Nb, the tubing extending continuously from its inlet to its outlet connection, although'it is looped in two difierent planes.

The particular continuous absorption system which I employ for circulating refrigerant is shown in a schematic diagram and fully described in the second of my above-mentioned patents. Accordingly, it is believed suflicient to merely briefly describe the system here.

Rich liquor (a refrigerant-absorbent mixture) is boiled in a still bythe application of heat, and

the refrigerant vapors are passed through analyzing and rectifying means to remove any entrained water vapors, then liquifled in an aircooled condenser. From the condenser the refrigerant is delivered (in liquid slugs separated by refrigerant vapor) to a receiving chamber or capillary tube housing M at the back of the food compartment. Liquid refrigerant in this receiver passes through a, capillary tube l5 and is delivered to the inlet end of the lower section of evaporator tubing I311, the details of this connectlon being described more fully hereafter. I

The liquid refrigerant vaporizes in the evaporator tubing, in a manner more fullydescribed in the first of my above-mentioned patents, and then passes out through the outlet and a pipe Hi to an absorber, where it is reabsorbed (at low pressure) in the absorbent liquid. In the case of. my particular system, the refrigerant is ammonia and the absorbent water.

The still and condenser of a water-ammonia absorption system operate at high pressure, generally from 150 to 250 pounds per square inch; and the evaporator and absorber operate at low pressure, generally from 10 to 20 pounds per square inch. In order to maintain the desired quantities and concentrations of liquid throughout the system, it is necessary to have a liquid circuit between the absorber and the still, moving weak liquor from the still to the absorber and rich liquor from the absorber to the still at intervals. This is accomplished by an intermediate transfer chamber which receives liquid from the absorber at low pressure and is then raised to high pressure to deliver it to the still. This basic system was fully illustrated and described in a number of issued Schurtz patents, a representative one in this regard being Patent No. 1,414,527, which issued May 2, 1922.

While the particular view shown in the accompanying drawing is a side elevation, and therefore does not make the continuity of the evaporator tubing perfectly obvious, it will be understood that there is a single continuous refrigerant flow path from the receiver to the outlet pipe I 6. While for purposes of manufacturing .convenience, thissingle continuous flow path may be formed by welding together various sections of tube, in finished form it is in eifect a single tube leading from its connection with the receiver to the lower horizontal plane, looping back and forth in that plane, passing up to and loo ing back and forth in a higher plane parallel to but spaced from the first-mentioned plane, and then connecting to the pipe l6. It will be noted that, in the arrangement shown here, all of the active or operative part of the evaporator is above the level of the receiver II. This complicates the problem of making a connection on the inlet side which does not frost back through the insulated wall, since all of the refrigerant delivered to the evaporator must, in effect, he forced up-hill from the point of delivery.

If all of the capillary tube were placed in the food compartment, on the inner side of the insulated wall, the problem would be greatly simplified. On the other hand, if the capillary tube could be split in the middle when it was desired to open the connection, trouble with frosting back might also be more easily overcome. The first of these alternatives i undesirable,- however, because it is desirable to'have the major portion of the capillary tube coiled in a helix (here identified as l5a) and lying within the receiver. The second is impracticable because any separation of a capillary tube throughout its course would result in almost inevitable plugging up of the tube when the parts were reconnected.

the capillary tube to be the function of the rat of delivery of the refrigerant to the receiver.

This is a very important factor in an absorption refrigerator, and has for the first time enabled the use of a capillary tube in such a. refrigerator. This desired automatic flow regulation can only be achieved where the receiver is hot, at substantially condenser temperatures; and the receiver cannot be kept hot unless it is on the outside of the insulated wall I I, and not within .the food compartment, where it would be cooled.

In order to enable the receiver and the major portion of the capillary tube to be located outside the food compartment wall, and to deliver refrigerant to a continuous tubing evaporator located above the level of the receiver. so that refrigerant works up through the evaporator to get the desired uniformity of cooling in the manner brought out in the first of my above-mentioned patents, I have devised the connection arrangement which is the subject matter of this application.

The inlet side of the evaporator tubing has a straight section 20 of small diameter, this section passing through the insulated wall II. The outer end of this section is provided with a fiange 2i permanently connected to it as bywelding, soldering and the like. As may be best seen in Figure 3, one end of the receiver I4 is provided The slugs of refrigerant are delivered to the receiver H from the condenser through a pipe- I! and a filter I8. When the refrigerant reaches the receiver It the liquid and vapor separate, as may be best seen in Figure 3, the liquid occupying the lower part of the receiver and the vapor the' upper part. Refrigerant in the receiver passes through another filter i8 and enters the inlet end of the capillary tube It, passing through the coils lid, and then along the straight portion i5b in which the capillary tube terminates. Heat transfer to .the liquid refrigerant passing through the capillary tube tends' to gasify it and retard its' flow; and practically all of the heat transfer is from condensation of hot refrigerant vapor in the upper part of the receiver on the exposed portions of the capillary coils. As was with a flange Ila adapted to be removably fastened to the flange 2|, as by the bolts 22. The straight end portion l5b of the capillary tube projects through an opening in the center of a plate member 23, the capillary tube being permanently sealed in this opening in any appropriate manner. When the parts are assembled, the capillary tube-plate-filter combination is placed in the position shown in the drawing, with the straight end portion of the capillary tube slipped into the straight section of tubing 20. Then the receiver I4 is brought into place over the outer end of this combination and the flanges joined together, gaskets 24 preferably being used to provide a good seal.

The straight portion 15b of the capillary tube is preferably a close but sliding fit, with only a very few thousandths of an inch difference in the external diameter of the capillary tube and the internal diameter of the section 20. The space between the outer wall of the capillary tube and the inner .wall of the section 20 of tubing should be so small that refrigerant will not pass through it. Under these conditions refrigerant is delivered from the outlet end of the capillary tube (the left-hand end in Figure 3) to a larger diameter section of the evaporator tubing, and at a point well within the food cornyet the connection issuch that it is readily removable, and unbolting the flanges enables the capillary tube to be removed and replaced, the filter l9 to be serviced, and the like.

and an evaporator therein'having an inlet, refrigerant controlling and expansion apparatus, including: a section of straight tubing of small diameter extending through one of the insulated walls, the inner end of said section opening into the inlet of the evaporator; and a capillary tube having the major portion thereof outside of said one insulated wall and terminating in a straight portion received by said section of tubing in a close fit, the inner end of the capillary tube extending within said insulated wall.

2. In combination with a refrigerator cabinet I with a food compartment having insulated Wallis and an evaporator therein having an inlet, re-

i'rigerant controlling and expansion apparatus, including: a section of straight tubing of small diameter extending through one of the insulated walls, the inner end of said section opening into the inlet of the evaporator; a chamber outside of said one insulated well adapted to receive liquid refrigerant; and a capillary tube having the maior portion thereof in, said chamber and terminating in a straight portion received by said section in a close but removable fit, the inner end of the capillary tube extending within said insulated wait.

3. hpparetus oi the cheracter claimed in claim 2, wherein the outer end of said section of tubing is provided with a henee and there is a coopersting member permanently connected to the capillary tube and removably connected to the first mentioned dance.

4. In combination with a refrigerator cabinet with a food compent having insulated walls and an evaporator therein having an inlet, refrigerant controlling and expansion apparatus, including: a section of straight tubing oi small diameter extending through one of the insulated walls, the inner end of said section opening into the inlet of the evaporator and at least the outer end thereofbeing lower than the evaporator. the outer end being provided with a we; a chamher outside oi said one insulated well adapted to receive liquid refrigerant; and a capillary tube having the major portion thereof coiled in said chamber and testing in a straight portion received by said section in a close but removable fit, the inner end of the capillary tube extending within said insulated wail, the chamber being provided with a a e, the capillary tube being provided with a plate uiernhor through which the straishtportion or the capillary tube proieets and to which it is permanently connected,

this member being removehiy seated between idfianges.

I 5. in combination with a refrigerator cabinet with a food compartment having insulated walls and an evarator'conduit therein, said evaporator comprising part of the low pressure portion of the refrigerator and there being a conduit in the high pressure portion, refrigerant flowcontrolling apperstus connecting said conduits, 

